<!DOCTYPE html>
<html language="en">
  <head>
    <title>a.com</title>
    <script language="javascript">
      function onLoad() {
        // The embedded iframe is dynamically loaded because we don't know
        // the port where it is hosted until runtime.
        console.log("a_embeds_a.html loaded");
        let l = window.location;
        let url = `${l.protocol}//a.com:${l.port}/a.html`;
        console.log(`loading iframe [${url}]`);
        let iframe = document.createElement('iframe');
        iframe.setAttribute('src', url);
        document.body.appendChild(iframe);
      }
    </script>
  </head>
  <body onload="onLoad();">
    Welcome to a.com, embedding a.com!
  </body>
</html>
